1. Field of the Invention
The present invention relates to a container packaging apparatus, and in particular to a container packaging apparatus for packaging a container, for example, a wafer case containing a plurality of semiconductor wafers therein, so as to be packed in a packaging bag, such as a plastic bag.
2. Description of the Related Art
In order to prevent any damage or contamination during being transported, semiconductor wafers, such as silicon wafers, which have been manufactured in a wafer manufacturing plant are, in a typical practice of packing, loaded into a wafer cassette, an intermediate holder, made of synthetic resin, which is in turn packed in a wafer case whose cover can be closed tightly via a gasket (a packing member). The wafer case is further packed firstly in an inner bag made of nylon (the trade name of polyamide fiber) and then in an outer bag made of aluminum, in which the wafer case may be enclosed in respective bags via heat sealing. This provides a packaging structure that can prevent any external fine dust or the like from entering into the wafer case to form a deposit on the wafer surface during the transporting operation.
To carry out manually the packaging procedure as described above, firstly the container is inserted into the packaging bag, and then the packaging bag in its sealing area is set in a heat sealing machine or a pressure sealing machine which may carry out the sealing operation with or without deaeration. Subsequently, an opening region and a rear end portion located opposite to the opening region of the packaging bag are folded manually, and both of the end portions of the packaging bag are fixed securely with tape attached thereon, respectively.
If all of the above steps are carried out manually, it takes a considerably long time to accomplish the packaging procedure and adversely it tends to develop crimps in the sealed area. In addition, when carrying out the packaging process incorporated with the deaeration effective in the bag, the condition after the deaeration varies widely, inhibiting the stable packaging procedure to be accomplished. Further disadvantageously, the process of folding and fixing the end portions of the packaging bag by attaching the tape has also imposed a lot of troubles.
There is one known apparatus to address the above problem, including a container packaging apparatus as disclosed in the cited reference, Patent Document No. 1, for example. The container packaging apparatus disclosed by the cited patent document No. 1 allows for the packaging procedure to be carried out by the divided steps, where the container packaging apparatus comprises: a packaging bag supply means for supplying a transverse-mounted packaging bag into a predetermined position; a container loader means for supplying a container to be packed into a predetermined position; a container insertion means operable to hold by vacuum chuck an opening region of a packaging bag with the aid of a pair of vertically arranged suction arms so as to open the packaging bag in the site of the opening region by moving each of the pair of suction arms vertically away from each other and subsequently to insert the container into the packaging bag through the opening of the bag; a shaping means operable to deaerate the packaging bag containing the container packed therein by a suction nozzle and subsequently to make a seal for closing the opening; and a packaging bag end portion processing means operable to fold an end portion of the sealed packaging bag and fix the folded end portion of the packaging bag.
According to the cited Patent Document No. 1, in the packaging process for carrying out the steps including: inserting the container into the packaging bag; deaeration and packing of the container; heat sealing in the opening of the packaging bag; folding the end portion of the packaging bag; and attaching the tape (label), the packaging apparatus can make the packages uniform in their quality, even if containers different in size, shape or the like are mixedly transferred through respective steps, so as to facilitate mechanization and automation of respective processes and thereby improve a throughput in the packaging procedure.
[Patent Document No. 1]                Japanese Patent Laid-open Publication No. 2002-154505        
However, the cited Patent Document No. 1 has the following drawbacks in association with the operation of inserting the container into the packaging bag.
Specifically, when the container is inserted into the packaging bag, triangular ear portions emerge in both sides of a rear end portion of the packaging bag as the container is advanced into the bag until it comes into abutment on a bottom portion of the packaging bag. In a region of a root of each triangular ear portion, it can be often observed that the triangular ear portion appears as inflated with air trapped inside thereof, which air is attributable to a folding line originally existing in either side of the packaging bag that has been placed in a flat configuration.
As in such a condition, an orientation of the triangular ear portion to be folded back over a side surface of the container in a subsequent operation would vary, inhibiting a folding back operation of the triangular ear portion from being carried out stably with an end of the triangular ear portion defined in the root region side (a side of the triangle of ear portion defined in the root side) taken as a base line for the folding back. Consequently, the triangular ear portions in the both sides of the bag rear end portion have often emerged unevenly, thus reducing (deteriorating) a finished condition of the packaged container.
In the light of the above circumstances, the inventors of the present invention have made an enthusiastic research and reached an idea that, prior to folding back the triangular ear portion over a side surface of the container, an ear folding and shaping bar should be pressed against a root of each triangular ear portion in its side to be folded back so as to crease it with a folding-back line that would be serving as a guide for folding back the triangular ear portion. The inventors has finally accomplished the present invention based on a further finding that if the above idea is brought into practice, the air trapped inside the triangular ear portion can be successfully exhausted, so that the triangular ear portions in the both sides of the bag rear end portion can appear uniformly in its size and shape and thus the packaging of the container can be provided with a high level of quality in a stable manner.